The present invention relates to a process of preparation of novel Mannich Bases from hydrogenated and distilled Cashew Nut Shell Liquid (CNSL) for use as additive in liquid hydrocarbon fuels for removing and protecting build up of deposits on carburetor surfaces and intake valve systems in a gasoline powered engine system.
Typical middle distillate hydrocarbon fuels, boiling in the gasoline range and used in spark-ignition internal combustion (IC) engines often contain components, which possess low volatility or solubility in the fuels. In practice such components tend to form deposits in the fuel carburetion system where fuel vaporization occurs. Deposit accumulations on carburetor throttle body and plates and intake valves lead to progressively poorer engine performance such as improper or rough idling of the engine, excessive consumption of fuel and the increased level of hydrocarbons and partially burned fuel components in the exhaust gas. Chemicals, which prevent or eliminate deposits in carburetor and intake valve systems, contribute significantly not only to automotive efficiency and economy of operation but also to minimizing pollution of the environment.
Deposits thus accumulated may be removed periodically by physical cleaning during engine overhaul or tune-up. A more preferred option to the deposit problem requires no interruption of engine usage and this is usually accomplished in practice by inclusion of a chemical composition known as carburetor detergent additive in the gasoline fuel.
There is a growing need for a chemical or chemical composition possessing detergency properties such that carburetor deposits may be completely eliminated. The importance of this need is now emphasized by the widespread awareness of pollution problems and the desire to minimize the emission of pollutants from automotive exhaust systems.
As a thumb rule, carburetor detergent additives must be soluble in the hydrocarbon fuel composition and possess a suitable balance of lyophilize and hydrophilic properties. Addition of carburetor detergents usually result in alleviating the deposits problem, however, they may exhibit hydrophilic surface-active properties to such a degree that water suspension (haze) and emulsion formation may occur. Therefore, there is a need for a suitable carburetor detergent additive for automotive systems, which should be effective in removing and preventing deposits on carburetor surfaces while exhibiting no undesirable effects upon other properties of the gasoline.
Newer generation designs for automotive power units make provision for recycle of gases which contain some partially oxidized hydrocarbons having a tendency to form deposits at or near the intake valves. Accordingly, suitable detergent additives for use in automotive fuels must be capable of keeping intake valves clean. There is, therefore, also a need for a suitable intake valve detergent additive for automotive systems effective in removing and preventing deposits in the intake system while exhibiting no undesirable effects upon other properties of the hydrocarbon fuel. Ideally, a suitable detergent additive for use in gasoline range hydrocarbon fuel will provide and maintain a high degree of cleanliness in both carburetor and intake systems.
Polar grouping suitable for inclusion in oil-soluble surface-active agents is the basic amine grouping and a non-polar grouping for such agents is the alkylaryl group usually provided by alkylation of phenols. Such polar and non-polar groups may be conveniently brought together in one molecular by the well-known Mannich condensation reaction involving an alkyl phenol, a low molecular weight aldehyde and an amine.
The alkyl phenol used in the process is hydrogenated and distilled Cashew Nut Shell Liquid (popularly known as CNSL) obtained after the hydrogenation of naturally occurring, biodegradable, vegetable based Cashew Nut Shell Liquid. CNSL occurs as a reddish brown viscous liquid in the soft honeycomb structure of the shell of cashewnut. CNSL, extracted with low boiling petroleum ether, contains about 90% anacardic acid and about 10% cardol. CNSL, on distillation, gives the pale yellow phenolic derivatives, which are a mixture of biodegradable unsaturated m-alkylphenols, including cardanol. Catalytic hydrogenation of these phenols gives a white waxy material, predominantly rich in tetrahydroanacardol which is also known as hydrogenated CNSL.
CNSL and its derivatives have been known for producing high temperature phenolic resins and friction elements, as exemplified in U.S. Pat. Nos. 4,395,498 and 5,218,038. Friction lining production from CNSL is also reported in U.S. Pat. No. 5,433,774. Likewise, it is also known to form different types of friction materials, mainly for use in brake lining system of automobiles and coating resins from CNSL.
Mannich condensation reactions usually proceed with the formation of high molecular weight products, by linear growth due to the use of mono-substituted phenols and an amine groups. Excess aldehyde may also react with amine groups to form imines or hydroxymethylamines.
Accordingly, the properties of such polymeric compositions have principally been utilized in heavier fuels such as heating and furnace oils, as described in US. Pat. No. 2,962,442, and in lubricating oils, as disclosed in U.S. Pat. Nos. 3,036,003 and 3,539,633. None of these uses involves a sensitive carburetion system as is found in the gasoline-powered spark-ignition internal combustion system.
Mannich condensation products have often been employed as stabilizers, or antioxidants, as well as dispersants, or detergents, in heavy hydrocarbon stocks. Use in lighter hydrocarbon stocks such as gasolines, has been disclosed in U.S. Pat. Nos. 3,269,810 and 3,649,229. U.S. Pat. No. 3,235,484 (Now U.S. Pat. No. Re. 26,330) describes the addition of certain disclosed compositions to refinery hydrocarbon fuel stocks for the purpose of inhibiting the accumulation of carbonaceous deposits in refinery cracking units. The primary inhibitors disclosed are mixtures of amides, imides and amine salts formed by reacting an ethylene polyamine with hydrocarbon substituted succinic acids or anhydride, whose hydrocarbon substituaent has at least about 50 carbon atoms. As an adjunct for such primary carbonaceous deposit inhibitors there is disclosed in said patent Mannich condensation products formed by reacting (1) alkylphenol, (2) an amine and (3) formaldehyde in the ratio of one mole alkylphenol and from 0.1-10 mole each of formaldehyde and amine reactant.
U.S. Pat. No. 3,368,972 describes dispersant-detergent additive for lubricating oils as high molecular weight Mannich condensation products from (1) high molecular weight alkyl-substituted hydroxyaromatic compounds whose alkyl-substituent has a molecular weight in the range of 600-3000, (2) a compound containing at least one HN less than  group and (3) an aldehyde in the respective molar ratio of 1.0:0.1-10:1.0-10.
The high molecular weight Mannich condensation products of either U.S. Pat. No. 3,235,484 or U.S. Pat. No. 3,368,972 have a drawback in their large-scale preparation and in their extended service used as lubricant addition agents used under high temperature conditions such as encountered in diesel engines. In the large-scale or plant preparation of such high molecular weight condensation products, especially in light mineral oil solvents, the resulting oil concentrate solution of the condensation product either has or develops during storage a haze which is believed to be caused by undissolved or borderline soluble by-products which not only are not substantially incapable of removal by filtration but also severely resurrect product filtration rate. When used in diesel engine crankcase lubricant oils and subject to high temperature in service use, piston ring groove carbonaceous deposits and skirt varnish tend to build up sufficiently rapidly and prevent desirable long in-service use of such lubricant oils.
A combination of diamine and higher polyamine Mannich condensation products useful in gasoline as carburetor detergents and useful also to control intake valve deposits and quick-heat intake manifold deposits has been disclosed in U.S. Pat. No. 4,038,044.
Various olefin polymers have been added to hydrocarbon fuels ranging from gasolines to diesel fuels to heavy oil fractions. Petrolatum have also been employed in gasolines. One example of such use of certain olefin polymers is described in U.S. Pat. No. 3,502,451, where gasoline motor fuel is claimed to be improved in its ability to maintain cleanliness of intake valves and parts.
The object of this invention is to provide a process for the preparation of novel Mannich bases from hydrogenated and distilled CNSL utilizing optimum reaction conditions of pressure temperature and proportion of all the reactants.
Another object of this invention is to propose a process for the preparation of Mannich bases from CNSL and their use as additive to improve gasoline fuels which shall be capable of substantially removing and protecting buildup of deposits on carburetor surfaces and intake valve system in a gasoline powered engine system.
To achieve the said objectives the present invention provides a process for the preparation of novel Mannich bases from hydrogenated and distilled Cashewnut Shell Liquid (CNSL) for use as additive in hydrocarbon fuels for removing and protecting build up of deposits on carburetor surfaces and intake valve systems in a gasoline powered engine system comprising:
reacting hydrogenated and distilled Cashew Nut Shell Liquid (CNSL), an amine having at least one reactive hydrogen atom, and an aldehyde in the molar ratio of 1:0.1 to 10:0.1 to 10 at a temperature ranging from 70xc2x0 C.-175xc2x0 C. for 6 to 12 hours in presence of an organic solvent,
distilling said solvent and unreacted amine, and
cooling and filtering the reaction product to obtain Mannich base
The trace solvent and unreacted amine are distilled off under high vacuum at 140-150xc2x0 C.
The said solvent is aprotic or protic solvents. Said protic solvent is alcohol and said aprotic solvent is selected from benzene, toluene, xylene or solvent-refined neutral oil.
The said amine is selected from the group consisting of primary and secondary alkyl/alkylaryl amines having an alkyl chain ranging from C1 to C20 or mixtures thereof preferably from C4 to C8.
The said amines include the mono and di-amino alkanes and their substituted analogs such as methylamine, ethylamine, dimethylamine, diethylamine, 2-ethylhexylamine, bis(2-ethylhexyl)amine, dimethylaminopropyl amine, diethanol amine, dipentyl amine, dicyclohexylamine, di-n butylamine; aromatic diamines, such as phenylene diamine, diamino naphthalenes; heterocyclic amines, e.g., morpholine, pyrrole, pyrrolidine, imidazole, imidazolidine, and piperidine; melamine and their substituted analogs.
The molar ratio of the reactants, Cashew Nut Shell Liquid (CNSL): an amine: an aldehyde is 1.0:1.0-1.2:1.0-1.2.
The said temperature at which the reaction is carried out is preferably 90xc2x0 C.
The said aldehyde is an aliphatic aldehyde such as formaldehyde (including paraformaldehyde and Formalin) or formaldehyde yielding reactants, acetaldehyde and aldol (xcex2-hydroxybutyraldehyde).
At least one amine and aldehyde are present in stoichiometric ratios of 1:1.
This invention further relates to a liquid hydrocarbon combustion fuel comprising:
a major portion of liquid hydrocarbon combustion fuel, preferably any gasoline base stock intended for use in spark-ignition internal combustion engines boiling within the range from about 10 deg. C. to about 220 deg. C. and derived from cracking, reforming, alkylation, polymerization and distillation operations conventionally employed in the petroleum refinery: and,
remainder Mannich base which is a condensation product of hydrogenated and distilled Cashew Nut shell Liquid, at least one amine and an aldehyde as prepared by the aforesaid process
The said additive is present in an amount ranging from 0.005 to about 1% by Weight, preferably 0.01 to about 0.5% by weight.
The invention will now be described with reference to the foregoing examples.